1. Field of the Invention
The invention relates to an improvement in tamper-proof closures, in particular, those closures having an annular, frangible tamper-proof band depending from the lower annular edge of the closure skirt and including a pull tab to facilitate removal of the tamper-proof band.
2. Description of the Prior Art
Tamper-proof closures have long been in use. The typical tamper-proof closure comprises a disc shaped panel, and an annular skirt depending from the periphery thereof. An annular tamper-proof band is attached by frangible means to the lower annular edge of the skirt. The tamper-proof band is adapted to engage an associated container finish, by any of several known means. For example, U.S. Pat. No. 3,980,195 to Fillmore discloses a closure including a tamper-proof band having inwardly projecting teeth engaging complementary outwardly projecting lugs on the container finish, to prevent rotational removal of the tamper-proof closure. Alternately, the tamper-proof band may engage an outwardly projecting bead formed on the container finish, either by being heat-shrunk onto the bead, or by being snapped into engagement with the bead.
In one type of tamper-proof closure, the band engages the container finish firmly enough to prevent removal of the closure while the tamper-proof band is still intact. To remove the closure, the tamper-proof band must first be removed from the closure skirt by tearing the frangible attachment means. The condition of the tamper-proof band will therefore provide a clear visual indication of whether the closure has been removed and reapplied, or whether an attempt has been made to tamper with the container. To facilitate removal of the tamper-proof band, these closures include a pull tab integrally formed on the tamper-proof band, by which the tamper-proof band can be grasped and removed.
Such tamper-proof closures therefore require two sequential operations by the user: first the removal of the tamper-proof band, then the removal of the closure itself, either by unscrewing or unsnapping the closure. However, these operations are not sufficiently complex for such closures to be regarded as child-resistant. Yet it is desirable to package many products in containers which have both a child-resistant feature and a tamper-proof or tamper indicating feature.